[PATCH] KEYS: trusted: allow trusted.ko to initialize w/o a TPM

[Jarkko Sakkinen]

Allow trusted.ko to initialize w/o a TPM. This commit adds checks to the
key type callbacks and exported functions to fail when a TPM is not
available.

Cc: Dan Williams <dan.j.willi...@intel.com>
Cc: sta...@vger.kernel.org
Fixes: 240730437deb ("KEYS: trusted: explicitly use tpm_chip structure...")
Signed-off-by: Jarkko Sakkinen <jarkko.sakki...@linux.intel.com>
---
 security/keys/trusted.c | 46 +++++++++++++++++++++++++++++++++++------
 1 file changed, 40 insertions(+), 6 deletions(-)

diff --git a/security/keys/trusted.c b/security/keys/trusted.c
index ecec672d3a77..13fb1068e371 100644
--- a/security/keys/trusted.c
+++ b/security/keys/trusted.c
@@ -135,6 +135,9 @@ int TSS_authhmac(unsigned char *digest, const unsigned char 
*key,
        int ret;
        va_list argp;
 
+       if (!chip)
+               return -ENODEV;
+
        sdesc = init_sdesc(hashalg);
        if (IS_ERR(sdesc)) {
                pr_info("trusted_key: can't alloc %s\n", hash_alg);
@@ -196,6 +199,9 @@ int TSS_checkhmac1(unsigned char *buffer,
        va_list argp;
        int ret;
 
+       if (!chip)
+               return -ENODEV;
+
        bufsize = LOAD32(buffer, TPM_SIZE_OFFSET);
        tag = LOAD16(buffer, 0);
        ordinal = command;
@@ -363,6 +369,9 @@ int trusted_tpm_send(unsigned char *cmd, size_t buflen)
 {
        int rc;
 
+       if (!chip)
+               return -ENODEV;
+
        dump_tpm_buf(cmd);
        rc = tpm_send(chip, cmd, buflen);
        dump_tpm_buf(cmd);
@@ -429,6 +438,9 @@ int oiap(struct tpm_buf *tb, uint32_t *handle, unsigned 
char *nonce)
 {
        int ret;
 
+       if (!chip)
+               return -ENODEV;
+
        INIT_BUF(tb);
        store16(tb, TPM_TAG_RQU_COMMAND);
        store32(tb, TPM_OIAP_SIZE);
@@ -967,6 +979,9 @@ static int trusted_instantiate(struct key *key,
        size_t key_len;
        int tpm2;
 
+       if (!chip)
+               return -ENODEV;
+
        tpm2 = tpm_is_tpm2(chip);
        if (tpm2 < 0)
                return tpm2;
@@ -1050,6 +1065,9 @@ static void trusted_rcu_free(struct rcu_head *rcu)
 {
        struct trusted_key_payload *p;
 
+       if (!chip)
+               return;
+
        p = container_of(rcu, struct trusted_key_payload, rcu);
        kzfree(p);
 }
@@ -1066,6 +1084,9 @@ static int trusted_update(struct key *key, struct 
key_preparsed_payload *prep)
        char *datablob;
        int ret = 0;
 
+       if (!chip)
+               return -ENODEV;
+
        if (key_is_negative(key))
                return -ENOKEY;
        p = key->payload.data[0];
@@ -1144,6 +1165,9 @@ static long trusted_read(const struct key *key, char 
__user *buffer,
        char *bufp;
        int i;
 
+       if (!chip)
+               return -ENODEV;
+
        p = dereference_key_locked(key);
        if (!p)
                return -EINVAL;
@@ -1170,6 +1194,9 @@ static long trusted_read(const struct key *key, char 
__user *buffer,
  */
 static void trusted_destroy(struct key *key)
 {
+       if (!chip)
+               return;
+
        kzfree(key->payload.data[0]);
 }
 
@@ -1245,9 +1272,13 @@ static int __init init_trusted(void)
 {
        int ret;
 
+       /* encrypted_keys.ko depends on successful load of this module even if
+        * TPM is not used.
+        */
        chip = tpm_default_chip();
        if (!chip)
-               return -ENOENT;
+               return 0;
+
        ret = init_digests();
        if (ret < 0)
                goto err_put;
@@ -1263,16 +1294,19 @@ static int __init init_trusted(void)
 err_free:
        kfree(digests);
 err_put:
-       put_device(&chip->dev);
+       if (chip)
+               put_device(&chip->dev);
        return ret;
 }
 
 static void __exit cleanup_trusted(void)
 {
-       put_device(&chip->dev);
-       kfree(digests);
-       trusted_shash_release();
-       unregister_key_type(&key_type_trusted);
+       if (chip) {
+               put_device(&chip->dev);
+               kfree(digests);
+               trusted_shash_release();
+               unregister_key_type(&key_type_trusted);
+       }
 }
 
 late_initcall(init_trusted);
-- 
2.19.1